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Applied Psycholinguistics 29 (2008), 627–667Printed in the United States of Americadoi:10.1017/S0142716408080272

Is overt repetition critical toexpressive word learning? The role ofovert repetition in word learning withand without semantics

BRANDON ABBS, PRAHLAD GUPTA, and NAVEEN KHETARPALUniversity of Iowa

Received: May 28, 2007 Accepted for publication: May 10, 2008

ADDRESS FOR CORRESPONDENCEPrahlad Gupta, Department of Psychology, University of Iowa, E11 Seashore Hall, Iowa City, IA52242. E-mail: [email protected]

ABSTRACTFive experiments examined whether overt repetition (i.e., saying a word aloud) during exposure iscritical to the expressive learning of new words. When participants did not engage in overt repetitionduring exposure, they nevertheless exhibited clear expressive learning, both with and without anaccompanying semantics, indicating that overt repetition is not critical to expressive word learning. Inaddition, learning without overt repetition did not differ from learning with overt repetition, suggestingthat overt repetition confers no benefit for learning in this situation. These results are discussed inrelation to previous studies, and it is suggested that benefits of repetition may accrue primarily insecond language rather than in first language word learning.

Is the spoken production of new words critical to their expressive learning? Thatis, can a learner acquire the spoken forms of new words without overtly speakingthem? The relevance of this question lies in its implications for understanding ofvocabulary acquisition in general, as well as in its implications for methods ofvocabulary instruction, which differ in their emphasis on the overt production ofnew vocabulary material. The answer to the question is not, however, obvious.Indeed, surprisingly little is known definitively about this issue.

Suppose, for instance, that a human infant was exposed to two languages thatwere equally represented in its linguistic environment (say, English and French).In one of the languages (say, French), the infant developed in typical ways, includ-ing engaging in linguistic communication receptively (showing comprehension)and expressively (making linguistic utterances). In English, however, the infantengaged only in receptive communication, never speaking. At age 3, would thischild have a typical expressive English vocabulary if tested through picture naming

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Applied Psycholinguistics 29:4 628Abbs et al.: The role of overt repetition in word learning

(e.g., via the Peabody Picture Vocabulary Test; Dunn & Dunn, 1997)? Note thatthe child would lack neither articulatory skill nor “having language,” becauseof his/her normal development in French. Demonstration of any expressive vo-cabulary would indicate that overt production is not an absolute necessity forsome expressive vocabulary growth to occur. Any difference in the size of his/herexpressive English vocabulary compared with that of peers would presumablybe attributable to a lack of overt production of words in English, and wouldindicate that overt production of words does aid in development of expressivevocabulary. Would the child demonstrate any expressive vocabulary knowledge?Would the size of his/her expressive vocabulary differ from that of peers? Thefact that we cannot be sure of the answer to these questions indicates that we donot know what role overt production plays in the expressive learning of spokenwords.

At least two kinds of overt production can be distinguished, based on the contextof production. One type of overt production occurs at the time of exposure to thesound pattern of the word (i.e., to the word form), in the form of immediaterepetition. We will term this overt repetition. A second type of overt productionis that occurring outside the immediate context of exposure to the word form, asin a spontaneous naming event or an utterance in which the word form is soughtout to be used, or in a picture-naming event. We term this overt naming. Here weare concerned with the role in expressive word learning (WL) of the former typeof overt production: overt (spoken) repetition.

Even with respect to this more limited sense of overt production, it is unclearhow crucial it is to WL. If the hypothetical child had never engaged in overt spokenrepetition, would s/he be able to engage in overt naming at all? Would the size ofhis/her expressive vocabulary differ from that of peers? Again, the answer to thesequestions is not definitively known.

Before turning to an examination of theoretical considerations as well as empiri-cal evidence that bear on these questions, let us clarify our usage of the term “wordlearning.” We adopt an operational definition of expressive WL: we treat it as beingmeasured by the increase in accuracy (over some number of exposures) of overtspoken production of the correct name in a novel name-referent pairing, when cuedwith the referent, that is, by the increase in accuracy of a particular type of overtnaming. We assume that such learning requires, at minimum (a) the establishmentof some internal representation of the referent (a semantic representation, whichmay or may not be very well specified), (b) the establishment of some internalrepresentation of the name (a phonological representation, which must eventuallybe specified well enough to support spoken production of the name), and (c)the establishment of a link from the former to the latter. In addition, what ismanifested as expressive WL very likely involves some facilitation of perceptualprocessing of the auditory novel name, as well as some facilitation of articulatoryprocessing in production of the novel name. These assumptions are little morethan a functional description of what must occur for expressive WL to be mani-fested; we therefore take these assumptions to be uncontroversial (see also Gupta,2005).

In expressive WL of this type, performance is gauged by production of thephonological word form. Accordingly, the aspect of expressive WL as described


above that was of primary interest in the present work was the learning of the in-ternal phonological representation. Furthermore, it is particularly in the formationof this phonological representation that the role of repetition has been thought toapply (e.g., Desrochers & Begg, 1987; Ellis & Beaton, 1993; see Gupta, 2005,for additional discussion of expressive WL). The aim of the present work wasthus to further clarify the role of repetition, by examining the effect of overtspoken repetition on establishment of the internal phonological representation inexpressive WL.

Let us further consider the critical independent variable of interest in our ex-amination of overt spoken repetition. To discuss this, it is necessary to providesome information about the experimental design adopted. As just indicated, thedependent measure was performance in an expressive WL task as described above,in which participants received multiple exposures to pairings of novel auditorynames with novel visual referents, and were tested on production of the nameswhen cued with the referents. That is, the dependent variable was correct namingperformance when cued with the referent. The manipulated variable was whetheror not participants were required to overtly repeat the names during exposuretrials, that is, whether or not the participants engaged in overt spoken repetition ofthe names during exposure trials.

What are the functional components of performance of overt spoken repetition ofa word form? At least two components are clearly identifiable: first, articulatory–phonological planning of the word form must occur. Second, the articulatory–phonological plan must be executed. A critical difference between the experimentalcondition in which participants perform overt spoken repetition compared withthe experimental condition in which participants do not perform overt spokenrepetition is this execution of the articulatory–phonological plan.

It is important to note here that we expected that participants would engage ininternal (silent) repetition, that is, internal rehearsal, in either or both experimentalconditions. Evidence for this comes from the work of Papagno, Valentine, andBaddeley (1991), who found that concurrent articulation interfered with learningthe pairings of known word forms with novel phonological word forms, but notwith other known phonological word forms. This indicated, first, that the locusof the effect of articulatory interference was at phonology, rather than in learningthe associative link, and second, that rehearsal, that is, silent internal repetition,was playing a role in the formation of the internal phonological representation.Thus, we expected participants to engage in internal rehearsal in the experimentalcondition that did not require overt spoken repetition.

What is this internal rehearsal? In our view, it can be considered to bearticulatory–phonological planning (see, e.g., Gupta & MacWhinney, 1995). Butthis means that articulatory–phonological planning may be expected to occur inboth conditions of our experimental design: both in the condition in which partic-ipants perform overt spoken repetition and in the condition in which participantsdo not perform overt spoken repetition. The critical difference between these twoconditions of the experimental design is then the execution of the articulatory–phonological plan. This differentiated the two conditions, and constituted the keyindependent variable of interest. A finding of significant WL in the no-overt repeti-tion condition would indicate that execution of the articulatory–phonological plan


is not necessary for learning of the internal phonological representations of wordforms. The finding of a difference between WL performance in the two conditionswould suggest that execution of the articulatory–phonological plan can play abeneficial role in learning of the internal phonological representation, whether ornot it is necessary.

Thus, the questions we ask in the present work are (a) whether overt spo-ken repetition (and in particular, overt execution of the articulatory–phonologicalplan) is necessary for establishment of the internal phonological representation inexpressive WL, and (b) whether overt spoken repetition (overt execution of thearticulatory–phonological plan) benefits establishment of the internal phonologi-cal representation in expressive WL. In the remainder of this article, we will usethe term overt spoken repetition as a shorthand for this critical variable we havediscussed, namely, overt execution of the articulatory–phonological plan.

In terms of theoretical or a priori considerations, there are reasons to posit aswell as deny a role for overt spoken repetition in expressive WL. In contrast,intuition and observation suggest that children do not consistently engage in overtrepetition, making it appear unlikely that it could be crucial to expressive WL.

The learning of word forms can be conceived of as very similar to the so-calledHebb effect. This effect refers to the finding that when subjects are presented withlists of digits for immediate serial recall, their recall improves for digit lists that,without the participant’s awareness, occur repeatedly, that is, learning of the listsoccurs (Hebb, 1961). However, when learning is measured through overt recall of alist, that is an oral response, the effect is dependent on participants’ overt repetitionof the lists during presentation (i.e., the opportunity to repeat the entire sequenceimmediately following presentation), and is not found without this overt repetition(Cunningham, Healy, & Williams, 1984). It has been argued that such learning isanalogous to that underlying expressive word form learning: in either case, what islearned expressively is a novel sequence of familiar items: a novel ordering of thephonemes of a language, in the case of word forms, and a novel ordering of digits,in the case of lists (Burgess & Hitch, 2005; Cumming, Page, & Norris, 2003; seealso Gupta, Lipinski, Abbs, & Lin, 2005). This would suggest that overt repetitionmay be critical to word form learning, and hence, to expressive WL.

In the language learning literature, evidence regarding the role of repetition ismixed. It has often been suggested that for learning of language as a whole (in-cluding not only vocabulary, but also pragmatics, grammar, etc.), rote repetitionand memorization is a less effective strategy than more engaging methods, suchas spaced recall (Atkinson, 1972; Royer, 1973). Further, the benefit of learninga language in context, such as through immersion, suggests that in comparison,rote memorization is not an effective language-learning tool. However, in second-language learners, evidence suggests that learners who generally dismiss rotememorization strategies as an effective way to learn the overall language stillendorse oral, or overt, repetition of a novel phonological form as an effectivestrategy for learning new words in a language, suggesting a specific role for overtrepetition in WL (Gu & Johnson, 1996). In this work, which studied adult Chinesenatives who were learning English, Gu and Johnson (1996) found that, in general,the most successful learners eschewed rote repetition in favor of more contex-tualized approaches for learning a language, but still endorsed overt repetition


as an effective rehearsal strategy for learning words. Further, this endorsementcorrelated significantly with a quantitative measure of English proficiency indi-cating that participants who believed that overt repetition of novel word formsimproved their subsequent memory for the word (and were presumably morelikely to engage in overt repetition) showed greater linguistic proficiency. Thiscorrelational study thus suggests a benefit for overt repetition. Others have alsosuggested a role for overt repetition in vocabulary acquisition (e.g., Kuhl, 2000;Studdert-Kennedy, 1986). For example, Kuhl and Meltzoff (1982, 1988) suggestedthat young children resort to a strategy of overt repetition of a heard sequence ofphonemes during the period of language acquisition, with the possibility that suchrepetition may be important to WL.

In the few experimental studies that have examined the effectiveness of variousrehearsal strategies in WL, overt repetition has been found to facilitate WL, buthas not been found to be critical (Duyck, Szmalec, Kemps, & Vandierendonck,2003; Ellis & Beaton, 1993; Papagno, Valentine, & Baddeley, 1991; Seibert,1927). These studies found that overtly repeating words during learning is a moreeffective method for vocabulary acquisition than either silent or visual methodsof rehearsal, but the silent and visual methods still showed significant learning.However, these studies focused more on associative learning between foreignlanguage words and native language translation equivalents, and examined whatrole Baddeley and Hitch’s (1974) phonological loop has in creating this link (butsee Duyck et al., 2003, Experiment 2). Further, these studies primarily examinedexpressive WL in terms of written, rather than spoken response, thus limiting theirimplications for early WL. Thus, these studies do not provide the strongest test of acritical role for overt repetition in expressive WL. Taken together, the correlationaland experimental data presented above provide some evidence for a role of overtrepetition in WL. They do not, however, directly examine whether overt repetitionis critical to expressive WL and have not always examined auditory presentationof word forms with performance measured through overt naming.

The approach in the present investigation is to directly examine the role ofovert repetition employing a paradigm in which participants were presented withauditory novel names and visually presented novel referents (rather than definitionsor translation equivalents), and asked to learn the names expressively, so that theycould subsequently produce the name of each novel referent, when cued withits visual depiction. We focused directly on two questions: (a) Can participantsdemonstrate expressive WL, in the absence of overt repetition? (b) Does any suchdemonstrated learning differ from that achieved in the presence of overt repetition?

EXPERIMENT 1

The task used to measure production is what we call an expressive recall (ER) task.In this task, participants go through a number of learning phases during whichthey are simultaneously exposed to novel auditory stimuli (hereafter, “nonwords”)and novel visual stimuli (line drawings of “space aliens”), and are asked to learnan association between the two, such that they can produce the nonword whenpresented with the space alien. In all of the WL experiments reported here, partic-ipants learned to produce three-syllable nonwords in response to the presentation


of its associated space alien by either overtly repeating the nonword during pre-sentation or simply being exposed to the nonword. Again, the hypothesis is thatonly participants who are given the opportunity to overtly repeat the nonword willdemonstrate the ability to produce the nonword upon presentation of the alien.

Method

Participants. Thirty-six undergraduates at the University of Iowa participated inthis experiment and received course credit in exchange for their participation.

Stimuli. All auditory and visual stimuli used in this experiment were randomlysampled from a larger corpus of experimental stimuli that have been systematicallyconstructed in accordance with English language phonology, but are completelynovel (Gupta et al., 2005). The auditory stimuli were three-syllable nonwords thathad a consonant–vowel (CV–CV–CVC) phonological structure (see Appendix Afor a full list of stimuli). The visual stimuli were line drawings of space aliensthat were drawn by a commissioned artist (see Appendix B for a sample of thesestimuli).

Design. The ER task can be broken down into two phases: an exposure phaseand a test phase, which are repeated multiple times and occur at regular intervals.

EXPOSURE PHASE. In the exposure phase, a participant is seated in front ofa computer screen and microphone while wearing a set of headphones. A seriesof five nonwords are presented over the headphones. On three of these exposuretrials, a foil nonword is presented and the participant sees only a black fixationcross on the computer screen in front of him. On the other two trials, a targetnonword is presented to the participant and is paired with a visual presentation offour aliens on the computer screen. One of these four space aliens is highlightedby the presence of a black box surrounding it; this alien is the referent for thetarget nonword. The participant is instructed that on these target exposure trials,the nonword presented is the name for the space alien that is surrounded by thebox and that the task is to associate this nonword with the alien (i.e., the referent).Further, the participant is instructed to learn a target–referent pair so that he canproduce the target when given the referent during the test phase. The other threealiens in the array can be thought of as visual distracters for this trial. For any givenexposure phase, the foil and target presentations alternate. Thus, an exposure phasehas the trial structure: Foil1, Target1, Foil2, Target2, Foil3. On Target2, a new targetnonword is presented along with the same aliens seen on Target1. The quadrant ofthe screen in which a space alien appears is randomly determined. Along with thenew nonword, a different alien is highlighted on Target2 than was highlighted onTarget1, but the instructions for the participant remain the same: to learn a target–referent pair so that he can produce the target when given the referent during thetest phase. Thus, each unique exposure phase (another unique exposure phase willbe introduced later) results in two target–referent pairs that the participant mustlearn. Whether a given pair occurs on Target1 or Target2 is randomly determined.


TEST PHASE. Following the exposure phase, a test phase occurs. In the testphase, the participant is again presented with the four alien array and the alienthat is the referent for one of the target nonwords is surrounded by a box, just asit was during exposure (although its location on the screen may have changed).Upon presentation of this array, the participant is instructed to say, out loud, thenonword that has previously been presented as the name for the alien during theexposure phase or “I don’t know” if he cannot remember the nonword. The orderof the target pair testing is randomly determined.

SETS. An exposure-test phase pairing (as was just described) can be thought ofas a self-contained “set” involving the presentation of two target–referent pairsand an immediate test of how well this pair was learned. Once a participant goesthrough one set (Set 1) of target–referent pairs, the process is repeated with anotherexposure–test phase pair (Set 2) that introduces two new target–referent pairs forthe participant to learn and immediately tests learning for just these pairs. At thispoint, the participant has gone through Set 1 and Set 2, during which he has beenexposed to and tested on four target–referent pairs. Together, these two sets canbe thought of as comprising an epoch (Epoch 1). Of importance, the auditory andvisual stimuli of Set 1 are completely independent of the stimuli of Set 2.

Once the participant has finished an epoch, there is a test phase that is theexact same structure as described above, but which tests learning for all four ofthe target–referent pairs, rather than the two most recently viewed pairs. This testis called a recap (Recap 1), and follows each epoch of learning. The order oftarget–referent pair testing is randomly determined.

Following completion of Recap 1 the participant begins Epoch 2, starting withthe exposure phase of Set 1. For each new exposure phase, unique foil nonwordsare presented to the participant, but the target–referent pairs remain the same.Thus, the target–referent pairs associated with Set 1 will always be associatedwith Set 1, although their presentation order within Set 1 will vary randomly (aspreviously discussed). Further, for each set, the visual array presented during eachepoch will contain the same stimuli as those presented in Epoch 1. One of thesedistracters was highlighted as the referent during Target2, but the other two remaininsignificant to the participant. Thus, the participant will be hearing different foilnonwords, the same target nonwords, and will see the same visual referents foreach set during each subsequent Epoch.

After Epoch 6, the participant engages in a paper and pencil distracter task(see below) for 6 min and then comes back to the computer screen for a finalrecap. This recap is the same as an epoch recap, but because it occurs following adistracter-filled time delay, it is designed to measure retention of the learning thattook place during the experiment.

DISTRACTER TASK. The distracter task is a semantic fluency task whereinparticipants are given the name of a category and asked to write down as manymembers of that category as they can think of in a 3-min time span. After thefirst 3 min passed, participants were given a second category and listed membersof that category for 3 min, for a total time of 6 min. The categories used in thisexperiment were occupations, animals, US states, and college majors. Occupations


and animals were always given together, as were US states and college majors,but any given participant only listed items from one of these two pairings duringthe 6 min between Recap 6 and Recap 7.

Procedure. All stimuli were presented on a Macintosh G3 PowerPC using theexperimental development program, PsyScope (Cohen, MacWhinney, Flatt, &Provost, 1993). Each experimental session was recorded on audiotape for laterreview and scoring. Participants were randomly assigned to one of two conditions:overt (N = 18), or silent (N = 18). In the overt condition, participants were askedto overtly repeat each of the nonwords they heard during the exposure phaseimmediately after they heard it. In the silent condition, participants were not askedto overtly repeat each of the nonwords; thus, they remained silent during theexposure phase and merely listened to each of the words that were presented tothem. Participants were also randomly assigned to the stimulus set that they wouldhave to learn. For this task, there were three sets of target–referent pairings that aparticipant could be asked to learn. Overall, 12 different target–referent pairingswere used in the ER task (see bold items in Appendix A). Any given participantwas trying to learn four pairs per task. One full epoch of practice, with separatepractice nonwords and space aliens used for presentation, was completed beforebeginning the experimental task.

Scoring.

ER. The main measure of interest is a participant’s recall performance at each ofthe recaps following the six epochs (subsequently referred to as Recap 1, Recap 2,etc.), and Recap 7. At each of these points, the participant response was examinedusing the audio recording of the experimental session. Each response was phonet-ically transcribed and compared to a phonetic transcription of the target nonwordas it was presented during the experiment. The transcriptions used a “Klattese”mapping of the International Phonetic Alphabet to standard computer keyboardcharacters (see table IV in Klatt, 1987). From this transcription, we obtained thepercentage of whole names, syllables, and phonemes correctly recalled at eachrecap of interest. Statistical analyses were done on all three levels of scoring togain an increased level of sensitivity in the measure.

Analysis. For each measure of the task a 2 (Condition) × 6 (Recap) mixed-design analysis of variance (ANOVA) was conducted to examine performanceat Recaps 1–6 and determine how much information was learned by each groupduring the course of the task and the trajectory of that learning. Then a separate2 (Condition) × 2 (Recap) mixed-design ANOVA was conducted to see if thethere was a significant change in performance from Recap 6 to Recap 7 and if thechange differed between groups. Recap 7 was not included in the initial ANOVAbecause the length and nature of the delay between Recap 6 and Recap 7 makeany comparison qualitatively different than a comparison between, for example,Recap 6 and Recap 5. Unless otherwise specified, an α level of .05 was adoptedfor each statistical test performed.


For the word and syllable measures, the number of possible values in each cellis small (for words: either zero, one, two, three, or four words correct), raisingthe possibility of nonnormality of distributions, and the possibility that parametrictests might be inappropriate. Examination of the error residuals of the ANOVAsfor words, syllables, and phonemes correct did, in fact, reveal those of words andsyllables to be nonnormally distributed. We therefore conducted a 2×6 and 2×2ANOVA on the rank transformation (equivalent to the Friedman two-way non-parametric ANOVA; Conover & Iman, 1981) of words and syllables correct forthis and the two word-learning experiments to follow. These ANOVAs are inaddition to the ANOVAs run with proportion correct as the dependent measure.The nonparametric results are presented in parentheses next to the parametricresults below.

Results

Words. For the 2 × 6 ANOVA, the main effect of recap was significant, F (5,170) = 21.17, p < .01, η2 = .38 (F [5, 170] = 20.71, p < .01, η2 = .38), butthere was no main effect of condition, F (1, 34) < 1, η2 = .002 (F [1, 34] < 1,η2 = .003), and no significant interaction, F (5, 170) < 1, η2 = .01 (F [5, 170] <1, η2 = .02). At Recap 6, the overt condition recalled 44.4% (SD = 25.1) of thealien names and the silent condition recalled an average of 43.1% (SD = 29.5).The learning trajectories for each group across the course of the experiment aredepicted in Figure 1.

The 2×2 ANOVA revealed a main effect of recap, F (1, 34) = 11.51, p < .01,η2 = .25, (F [1, 34] = 13.22, p < .01, η2 = .28) but no main effect of condition,F (1, 34) < 1, η2 = .02 (F [1, 34] < 1, η2 = .02), and no interaction effect,F (1, 34) = 1.56, p = .22, η2 = .04 (F [1, 34] = 1.14, p = .29, η2 = .03). AtRecap 7, the overt condition recalled an average of 36.1% (SD = 30.0) and thesilent condition recalled an average of 25.0% (SD = 27.1).

Syllables. The 2×6 ANOVA found a main effect for recap, F (5, 170) = 44.45,p < .01, η2 = .57 (F [5, 170] = 44.57, p < .01, η2 = .57), but no main effectof condition, F (1, 34) < 1, η2 = .0003 (F [1, 34] = <1, η2 = .002), and nointeraction effect, F (5, 170) < 1, η2 = .01 (F [5, 170] < 1, η2 = .02). At Recap 6,the overt condition could recall 64.4% (SD = 20.4) of the syllables and the silentcondition could recall 63.4% (SD = 26.4).

The 2×2 ANOVA showed a main effect of recap, F (1, 34) = 17.14, p < .01,η2 = .34 (F [1, 34] = 5.24, p < .05, η2 = .13), but no main effect of condition,F (1, 34) < 1, η2 = .01 (F [1, 34] < 1, η2 = .02), and no interaction effect, F (1,34) = 1.28, p = .27, η2 = .04 (F [1, 34] < 1, η2 = .002). At Recap 7, the overtcondition recalled 55.1% of the syllables (SD = 20.4) and the silent conditionrecalled 47.2% (SD = 28.6).

Phonemes. The 2 × 6 ANOVA revealed a main effect of recap, F (5, 170) =60.91, p < .01, η2 = .64, with no main effect of condition, F (1, 34) < 1, η2 =.002, and no interaction, F (5, 170) < 1, η2 = .02. At Recap 6, the overt condition

Figure 1. The performance in Experiment 1 for participants in the silent and overt conditionsacross all seven recaps. Performance is measured as the proportion correct and is plottedseparately in terms of (top) words, (middle) syllables, and (bottom) phonemes correct. Errorbars are standard errors.


recalled 79.0% of the phonemes (SD = 16.6) and the silent condition recalled79.6% (SD = 22.0).

The 2×2 ANOVA revealed that there was a main effect of recap, F (1, 34) =25.84, p < .01, η2 = .43, no main effect of condition, F (1, 34) < 1, η2 = .01,and a borderline interaction effect, F (1, 34) = 3.95, p = .055, η2 = .10. At Recap7, the overt condition recalled an average of 71.4% (SD = 22.2) of the phonemesand the silent condition recalled an average of 62.2% (SD = 30.8).

Power analysis. We examined the sensitivity of the experiment, for each of theforegoing analyses, by assessing the size of the effect our tests can detect withpower of .80. This sensitivity was computed with the assistance of G*Power3 (Faul, Erdfelder, Lang, & Buchner, 2007), which implements the proceduresdescribed by Cohen (1988).

In the 2 × 6 ANOVAs, for the between-groups main effect of repetition, thisexperiment was capable of detecting a medium or large effect size of f ≥ .29(corresponding to η2 ≥ .08) with a power of .80. Similarly, for the within-groupmain effect of recap and the within-between interaction, a medium or large effectsize of f ≥ .23 (corresponding to η2 ≥ .05) would be detected. For smaller effectsizes, the execution of “retrospective power analyses” based on the “observedpower” implied by our data is highly criticized by statisticians as an invalid wayof assessing the validity of null effects (for a discussion, see Faul, Erdfelder,Lang, & Buchner, 2007; for criticism, see Gerard, Smith, & Weerakkody, 1998;Hoenig & Heisey, 2001; Kromrey & Hogarty, 2000; Lenth, 2001; Steidl, Hayes, &Schauber, 1997). One accepted way of assessing effects retrospectively is throughthe comparison of effect sizes (Zumbo & Hubley, 1998), which we have donein our discussion. Another alternative to a retrospective approach is to execute a“criterion analyses” that tells us how much we need to adjust our alpha level tosafely achieve a particular level of power. Such an analysis has its own critics (e.g.,Gigerenzer, Krauss, & Vitouch, 2004) will yield α levels far removed from thetraditional .05 level; however, its use in conjunction with an analysis of observedeffect sizes lessens these criticisms some. Thus, we executed a criterion analysisusing G*Power 3 and found that to detect a small effect ( f = .10) with a powerof .80, the α value of this experiment would need to be adjusted to .69 for thebetween-group effect and .60 for the within–between interaction. Such a changewould not change the significance for the main effects of learning reported here forwords, syllables, or phonemes. Further, it would not change the significance forthe interaction effects for words, or syllables, but would make the phoneme levelmeasure statistically significant. However, with an η2 value of .02 for this effect,the functional significance of such an effect in explaining the variance betweenthe overt repetition and silent group would be in doubt even if one accepted thestatistical significance following alpha level adjustment.

For the measures of retention (i.e., in the 2 × 2 ANOVAs), this experimentwas capable of detecting a large between-group effect ( f ≥ .42, corresponding toη2 ≥ .15), and a medium or large within-group and interaction effect ( f ≥ .24,corresponding to η2 ≥ .054) with a power of .80. The difficulty with detectingbetween-group effects lies in the strong correlation between the within-groupmeasures. To detect a small ( f = .10, which is closer to what is being observed in


these experiments) between-group effect with power of .80, the α level would needto be adjusted to .75. Such an adjustment would not make the between-groupseffects significant at either the word, or syllable level, but it would make an effectat the phoneme level significant. However, the functional significance of such aneffect would still be in question, as the maximum η2 for these effects is .01. Forthe interaction, an adjustment of α to .61 would need to be made to detect a smalleffect. Such an adjustment would make the interaction significant at the wordlevel, but not the syllable level. Once again, though, such an effect would accountfor just .04 of the variance in this measure.

It should be noted here that these sensitivity analyses will also apply to Experi-ments 2 and 3, as the paradigm (WL Task), measures (word, syllable, and phonemeaccuracy), experimental design (2×6 and 2×2 mixed design), and sample size(N = 36) of these experiments will not change.

Discussion

For the above analyses, one can think of the first analysis of performance, whichcompared performance at Recaps 1–6 as examining differences in learning acrossmultiple repetitions and retaining linguistic information across short time spans.The time between measurement points is small, less than 1 min, and is filled byexposures to the target stimuli as well as tests of even shorter term retention. Thesecond analysis, comparing Recap 6 with Recap 7, is one of long-term retentionwithout further exposure to the experimental stimuli. Here, the delay between testsis 6 min, and is filled by an irrelevant distracter task.

Performance at test was fairly low (fewer than two out of four of words cor-rectly recalled even after six recaps). This might appear to contrast with real-worldperformance, in that children are thought to learn new words in as little as oneexposure (“fast mapping”; Carey, 1978). It may therefore be worth emphasizing thefact that the phonological targets in the present experiment were three syllableslong, in contrast with the one-syllable words typically studied in fast mappingsituations. Learning trisyllabic phonological forms can, of course, be expectedto be considerably slower than learning monosyllabic forms. In addition, recentevidence (Horst & Samuelson, in press) indicates that real-world “fast mapping”is actually much less fast than previously believed. Learning in the present exper-iments therefore does not, in fact, appear to be particularly slower than real-worldlearning.

It is also worth reiterating that we expected participants in the silent condi-tion to be rehearsing silently, that is, engaging in what we previously termedinternal repetition. As noted in the Introduction, the literature indicates thatinternal repetition/rehearsal may be important for expressive WL (e.g., Duycket al., 2003; Papagno et al., 1991), although its role may depend on aspects of theexperimental paradigm, a point we return to in the General Discussion. Furtherinvestigation of the role of internal repetition, especially in a paradigm of thepresent kind, is therefore an important question for future research. However,the focus of the present investigation is on what role overt (spoken) repetitionplays (and in particular, what role execution of the articulatory–phonologicalplan plays), which is a question that has hitherto remained unanswered, and


whose importance is independent of whether or not internal repetition plays arole.

With regard to overt repetition, the two questions of interest were (a) whetherexpressive learning would occur without overt repetition, and (b) whether overtrepetition would be beneficial to WL. The robust learning observed in the silentcondition with all three types of scoring (word level, syllable level, and phonemelevel) indicates clearly that learning can occur in the absence of overt repetition,which is therefore not critical to expressive learning. Experiment 1 thus providesstrong evidence regarding our first question of interest.

Turning to the second question, there was no evidence for a benefit of overtrepetition in the 2 × 6 ANOVAs. Although there was a significant effect of re-cap, establishing that participants in this experiment were learning, there was noRecap × Condition interaction that would suggest differential learning based onwhether or not a participant was engaging in overt repetition. Learning clearlyoccurs in the silent group and the acquisition trajectory is no different for eithergroup. These results hold no matter the level of analysis for accuracy (i.e., words,syllables, or phonemes correct).

The effect size and sensitivity analyses are relevant to interpreting these nulleffects. For the 2 × 6 ANOVAs, the main effect of condition and the Recap ×Condition interaction accounted for at most 2% of the variance in the data (η2 =.02), in the various analyses. This corresponds to an effect size index of f = .143,classified by Cohen as a small effect size (Cohen, 1988). Our sensitivity analysesconfirm that the experiment was capable of detecting moderate to large effectswith a power of 0.80, and therefore would (with 80% probability) have yieldeda significant main effect of Condition or Recap× Condition interaction had anysuch effect been of even moderate size. The effect size and sensitivity analysesthus provide evidence that overt repetition does not contribute in any substantialway to expressive WL. However, it remains possible that there is a small beneficialeffect of overt repetition on expressive WL, accounting for on the order of 1–2%of variance in the experimental data.

For the longer term retention examined by the 2×2 ANOVAs, the effect sizefor the interaction was larger than for any other nonsignificant result (η2 = .10,which corresponds to an effect size index of f = .333, classified by Cohen as amedium effect size). Our sensitivity analyses indicate that the experiment wascapable of detecting a medium or large effect size with a power of 0.80. Thisis consistent with the borderline significant interaction in the long-term retentionof phonetic information, wherein participants in the overt group recalled morephonemes of the words that they were trying to learn following a 6-min task-filleddelay. This borderline effect suggests that although overt repetition is not criticalto acquisition, it may be critical to retention, a qualitative distinction that has alsobeen made in other literatures (cf. Schmidt & Bjork, 1992). Participants appear tobe affected by the repetition manipulation in such a way that overt repetition aidsthe establishment of longer term expressive representations of word forms. Havingdetermined that participants can acquire new words in an expressive learning taskwithout overt repetition and received some information that participants may differon their retention of these words as a function of repetition, we turn now to thequestion of whether participants can retain new words over long delays without


overt repetition. To do this, we extend the delay imposed in Experiment 1 to adelay of more than 23 hr.

EXPERIMENT 2

Experiment 2 is designed to extend the delay between the final exposure and finaltest to determine if overt repetition is critical to retention with an approximately23-hr delay. If any benefit of overt repetition is related to retention, and thus timedependent, then extending the delay could lead to a greater benefit for the overtrepetition condition over the silent condition. In addition, if the benefit is timedependent, then such a finding would provide information about the functionalsignificance of the delay effect seen in Experiment 1, because one might expectthat a “testing” situation (i.e., a situation in which one can demonstrate expressiveknowledge about a word) during natural language acquisition does not occur withinminutes of hearing a new word; rather, it occurs after longer periods of time (i.e.,hours or days). A corollary benefit to Experiment 2 is a complete replication ofExperiment 1 with a new set of stimuli, because the first session of Experiment 2will be identical to Experiment 1.

Method

Participants. Thirty-six participants were involved in this experiment. Five par-ticipants were recruited through a posting on the University of Iowa’s JobNetwebsite and received $16 for participating. The remaining participants were un-dergraduates at the University of Iowa and received course credit for participating.

Stimuli. All auditory and visual stimuli used in this experiment were randomlysampled from the same corpus as Experiment 1. None of the target–pair stimulioverlapped with the stimuli in Experiment 1 (see Appendix C).

Procedure. The procedure for Experiment 2, Session 1, was identical to that ofExperiment 1. Participants engaged in the ER task, including the distracter portionof this task. Stimuli were presented through the same apparatus and counterbal-ancing as well as the use of multiple stimulus sets was undertaken in the samemanner. Upon completion of the ER task, participants were instructed to return atthe same appointment time the next day. Participants were encouraged to avoidalcohol and recreational drugs and to get a full night’s sleep during their time awayfrom the lab. They were not told the nature of the tasks that they would be askedto complete during the next day’s session, Session 2.

During Session 2, participants first completed a recap test phase (delayed recap)that tested all four of the target–referent pairs that had been studied and testedduring Session 1. This test phase was conducted in the same manner as the recaptest phases completed the previous day. No further instructions or prompting wereprovided beyond the referent for the target nonword that the participant was toproduce.


Scoring and analysis. Responses were scored using the same criteria and methodas Experiment 1. An additional 2 × 2 mixed-design ANOVA was conducted toassess the difference in accuracy at the end of Session 1 (final recap) and thebeginning of Session 2 (delayed recap).

Results

Words. The 2×6 ANOVA revealed a main effect of recap, F (5, 170) = 19.66,p < .01, η2 = .37 (F [5, 170] = 19.54, p < .01, η2 = .37), no main effect ofcondition, F (1, 34) < 1, η2 = .005 (F [1, 34] < 1, η2 = .009), and no interaction,F (5, 170) < 1, η2 = .01 (F [5, 170] < 1, η2 = .02). At Recap 6, the overt andsilent condition both recalled 41.7% of the space alien names (see Figure 2).

The 2×2 ANOVA assessing the change in learning from Recap 6 to Recap 7showed a significant effect of Recap for the parametric test, but not for thenonparametric, F (1, 34) = 5.29, p < .05, η2 = .13, (F [1, 34] = 2.37,p = .13, η2 = .07), no main effect of condition, F (1, 34) < 1, η2 = .0001(F [1, 34] < 1, η2 = .0003), and no interaction, F (1, 34) < 1, η2 = .001(F [1, 34] < 1, η2 = .001). At Recap 7, the silent condition recalled 34.7% of thealiens (SD = 33.4) and the overt condition recalled 33.3% (SD = 32.1).

The 2×2 ANOVA assessing the change in learning from Recap 7 to the delayedrecap, showed a main effect for recap, F (1, 34) = 5.64, p < .05, η2 = .14 (F [1,34] = 7.15, p = .01, η2 = .18), no main effect for condition, F (1, 34) < 1, η2 =.0002 (F [1, 34] < 1, η2 = .0001), and no interaction, F (1, 34) < 1, η2 = .001 (F[1, 34] < 1, η2 = .008). Upon return to the lab, participants in both the silent andovert condition recalled 25.0% of the space alien names, which was significantlyabove 0 for both groups combined, t (35) = 4.66, p < .01, d = .78.

Syllables. The 2×6 ANOVA found a main effect for recap, F (5, 170) = 44.66,p < .01, η2 = .57 (F [5, 170] = 44.67, p < .01, η2 = .57), no main effect ofcondition, F (1, 34) < 1, η2 = .01 (F [1, 34] < 1, η2 = .01), and no interactioneffect, F (5, 170) < 1, η2 = .03 (F [5, 170] < 1, η2 = .03). At Recap 6, the overtcondition could recall 62.0% (SD = 30.3) of the syllables and the silent conditioncould recall 63.9% (SD = 28.9).

The 2 × 2 ANOVA (Recap 6–final recap) for showed a main effect of recap,F (1, 34) = 6.62, p < .01, η2 = .17 (F [1, 34] = 5.41, p < .05, η2 = .14), noeffect of condition, F (1, 34) < 1, η2 = .0001 (F [1, 34] < 1, η2 = .0005), andno interaction effect, F (1, 34) < 1, η2 = .02 (F [1, 34] < 1, η2 = .02). At Recap7, the overt condition recalled 56.0% of the syllables (SD = 28.8) and the silentcondition recalled 53.7% (SD = 30.7).

The additional 2 × 2 mixed-design ANOVA (final recap–next day) showed amain effect for recap, F (1, 34) = 18.11, η2 = .35 (F [1, 34] = 21.38, p < .05,η2 = .39), no main effect for condition, F (1, 34) < 1, η2 = .003 (F [1, 34] < 1,η2 = .008), and no interaction, F (1, 34) < 1, η2 = .001 (F [1, 34] < 1, η2 =.004). Participants in the silent recalled 37.5% (SD = 35.2) of the syllables andparticipants in the overt condition recalled 41.2% (SD = 32.6) of the syllables whentested at the delay recap. The combined performance of both groups (39.4%), wassignificantly above 0, t (35) = 7.05, p < .001, d = 1.18.

Figure 2. The performance in Experiment 2 for participants in the silent and overt conditionsacross the entire first session (Recaps 1–7) and the first test of the second session (Recap 8).Performance is plotted separately in terms of (top) words, (middle) syllables, and (bottom)phonemes correct. Error bars are standard errors.


Phonemes. A 2×6 mixed-design ANOVA found a main effect of recap, F (5,170) = 59.01, p < .01, η2 = .63, with no main effect of condition F (1, 34) =< 1, η2 = .02, and no interaction, F (5, 170) = 1.68, p = .14, η2 = .05. At Recap6, the overt condition recalled 76.5% of the phonemes (SD = 23.2) and the silentcondition recalled 77.5% (SD = 22.3).

A 2 × 2 mixed-design ANOVA (Recap 6–final recap) revealed that there wasa main effect of recap, F (1, 34) = 9.92, p < .01, η2 = .25, no main effect ofcondition, F (1, 34) < 1, η2 = .001, and no interaction effect, F (1, 34) < 1, η2 =.02. At Recap 7, the overt condition recalled an average of 70.1% (SD = 26.5)of the phonemes and the silent condition recalled an average of 67.8% (SD =26.2).

Again, the additional of 2×2 ANOVA (final recap–next day) showed a maineffect for recap, F (1, 34) = 20.50, η2 = .23, no main effect for condition, F (1,34) < 1, η2 = .0003, and no interaction, F (1, 34) < 1, η2 = .01. Participantsin the silent condition recalled 49.4% (SD = 37.8) of the phonemes in the spacealien names at the delay recap, whereas the overt condition recalled 55.3% (SD =33.1). The combined performance of both groups (52.3%) was significantly above0, t (35) = 8.93, p < .01, d = 1.49.

Criterion analysis. The power analysis of Experiment 1 also applies to Exper-iment 2 because it involves the same paradigm, measures, experimental design,and sample size. For learning, we previously determined that in order to detect asmall effect ( f = .10) with power of .80, the α of the experiment would need to beadjusted to .69 for the main effect and .60 for the interaction. Such a change wouldchange the significance for the main effects of learning reported for Experiment2 for words, syllables, or phonemes. Further, it would change the significancefor the interaction effects for syllables, and phonemes, but it would not affectthe significance of the word measure. However, the η2 values for these effectsrange from just .005 to .05, and they pale in comparison to the .37–.63 valuesfound for the recap effect. Thus, although an effect of overt repetition cannotbe unequivocally rejected on statistical grounds, its effect on learning is trivialcompared to the robust learning that silent participants demonstrate both here andin Experiment 1.

To detect a small ( f = .10) between-group effect with power of .80, the α levelwould need to be adjusted to .75. Such an adjustment would not make the between-groups effects of the initial 6-min delay (i.e., Day 1) or across the longer 23-hrdelay (i.e., Day 2) significant at either the word, syllable, and phoneme level. Forthe interaction effect, an α level of .61 would be needed to detect a small effect.This adjustment would not change the significance of the effect at the word orsyllable level, but would make the phoneme-level significant. However, we stressagain that such an effect accounts for little of the variance (η2 = .01) compared tothe extremely robust learning (d = 1.49) that is maintained at the phoneme levelacross both conditions.

Discussion

The result of Experiment 1 that indicated that overt repetition may benefit theretention of new words did not hold up in the face of replication or a more powerful


test of retention following an extended delay. Participants in the both conditionsshowed equivalent retention on Day 2 as evidenced by a lack of an interactionbetween conditions in the decrease from Day 1 to Day 2 and performance for bothgroups combined that was significantly above 0 on Day 2 for all measures.

The sensitivity analyses of Experiment 1 are also applicable to Experiment 2.These, together with the effect sizes reported above for Experiment 2, indicateonce again that had there been moderate to large effects of condition, or of theCondition × Recap interaction, the experiment would have detected them with80% probability, that is, with a power of .80 (except in the case of the retentionmain effect of condition, where only a large effect would be detected). In fact,however, these effects are small in all analyses. Thus, in Experiment 2, as inExperiment 1, the sensitivity analyses support the conclusion that overt repetitiondoes not contribute in any substantial way to expressive WL, although it remainsa possibility that there is a small beneficial effect of overt repetition on expressiveWL, accounting for on the order of 1–2% of variance in the experimental data.

Thus far, learning has been shown for participants who do not overtly repeata stimulus that they are later asked to expressively recall. Further, this learninghas been shown to be nearly identical to the performance of participants whoare overtly repeating the words given to them. However, the participants who arerepeating are not only repeating stimuli, but also receiving an additional stimuluspresentation provided by their vocalization. Given this confound, there remainsthe possibility that participants who do not overtly repeat may actually performbetter than participants who are not repeating if they are given the same numberof exposures during test. In the current design, overt participants are able to hearthe stimulus spoken by both a standardized voice and their own voice, whereassilent participants hear only the standardized voice. In Experiment 3, we attemptto completely equalize the experience of participants in both conditions to isolatethe effect of overt repetition and investigate whether there is a situation in whichparticipants who do not overtly repeat stimuli may exceed the performance levelof participants who do.

EXPERIMENT 3

The goal of Experiment 3 was to address the confound wherein participants in theovert condition enjoy the benefit of an additional stimulus presentation because oftheir own vocalizations. Given that the overt condition has thus far shown nearlyidentical learning to the silent condition, there is the possibility participants in thesilent condition might surpass the accuracy of participants in the overt conditionif they are given the same number of exposures to the to be learned word.

Method

Participants. Thirty-six undergraduates at the University of Iowa participated inthis experiment. They received course credit for their participation.

Stimuli. All auditory and visual stimuli used in this experiment were randomlysampled from the same corpus as Experiment 1. The nonwords presented to


participants were three syllables in length and had the same CV–CV–CVC pho-netic structure. However, the target–referent pairs were changed where necessaryto ensure that there was no overlap (in either target or referent) with the stimulipresented as targets and referents in Experiments 1 and 2 (see Appendix D).

Nonwords presented to participants in the silent condition were created usingthe editing software Sound Edit 16, Version 2. The original sound file was simplycopied and pasted next to itself in the editing palette, creating two copies of thenonword, side by side. The effect of this editing was to create a single soundfile that had two presentations of the same nonword, without a predeterminedinterstimulus interval. The only break between presentations was the poststimulussilence of the first presentation, which was minimal (<100 ms).

Procedure. Other than the change in stimuli for the silent condition, the procedurefor Experiment 3 was identical to that of Experiment 1. Participants engaged inan ER of identical structure and the same distracter task as Experiment 1. Stimuliwere presented through the same apparatus and counterbalancing and the use ofmultiple stimulus sets was undertaken in the same manner.

Scoring and analysis. Experiment 3 was scored and analyzed using the samecriteria and tests as Experiment 1.

Results

Words. The 2×6 ANOVA revealed a main effect of recap, F (5, 170) = 44.76,p < .01, η2 = .57 (F [5, 170] = 45.47, p < .01, η2 = .57), but no main effect forcondition, F (1, 34) < 1, η2 = .01 (F [1, 34] < 1, η2 = .003), and no interactioneffect, F (5, 170) = 1.28, p = .27, η2 = .04 (F [5, 170] = <1, η2 = .02). AtRecap 6, the overt condition averaged 56.0% names correctly recalled (SD =39.8) whereas the silent condition averaged 47.0% (SD = 27.0). Thus, despite theovert condition achieving higher levels of performance the magnitude of learningdid not significantly differ between groups (see Figure 3).

The 2×2 ANOVA revealed a statistical trend for a main effect of recap, F (1,34) = 3.86, p = .06, η2 = .10 (F [1, 34] = 2.79, p = .10, η2 = .08), no main effectof condition, F (1, 34) < 1, η2 = .02 (F [1, 34] < 1, η2 = .01), and no interactioneffect, F (1, 34) < 1, η2 = .001 (F [1, 34] < 1, η2 = .02). At Recap 7, participantsin the overt condition correctly recalled 48.6% of the words (SD = 33.7), whereasparticipants in the silent condition correctly recalled 38.9% (SD = 28.7).

Syllables. The 2×6 ANOVA revealed a main effect of recap, F (5, 170) = 64.68p < .01, η2 = .66 (F [5, 170] = 63.68 p < .01, η2 = .65), but no main effect forcondition, F (1, 34) < 1, η2 = .01 (F [1, 34] < 1, η2 = .01), and no interactioneffect, F (5, 170) < 1, η2 = .005 (F [5, 170] < 1, η2 = .007). At Recap 6, theovert condition averaged 70.8% syllables correctly recalled (SD = 31.1), whereasthe silent condition averaged 67.6% (SD = 27.2).

The 2 × 2 ANOVA revealed a statistical trend for a main effect of recap, F(1, 34) = 3.87, p = .06, η2 = .10 (F [1, 34] = 4.65, p < .05, η2 = .12), nomain effect of condition, F (1, 34) < 1, η2 = .01 (F [1, 34] < 1, η2 = .01), and no

Figure 3. The performance in Experiment 3 for participants in the silent and overt conditionsacross all seven recaps. Participants in the repeat condition of this experiment received twopresentations of all nonwords heard during the experiment. Performance is plotted separatelyin terms of (top) words, (middle) syllables, and (bottom) phonemes correct. Error bars arestandard errors.


interaction effect, F (1, 34) < 1, η2 = .02 (F [1, 34] < 1, η2 = .03). At Recap 7,participants in the overt condition correctly recalled 67.1% of the syllables (SD =26.6), whereas participants in the silent condition correctly recalled 58.8% (SD =23.1).

Phonemes. The 2 × 6 mixed-design ANOVA revealed a main effect of recap,F (5, 170) = 73.92 p < .01, η2 = .68, but no main effect for condition,F (1, 34) < 1, η2 = .0002, and no interaction effect, F (5, 170) < 1, η2 = .002.At Recap 6, the overt condition averaged 83.4% phonemes correctly recalled(SD = 21.7), whereas the silent condition averaged 83.1% (SD = 21.1).

The 2×2 mixed-design ANOVA revealed a main effect of recap, F (1, 34) =5.99, p = .02, η2 = .15, no main effect of condition, F (1, 34) < 1, η2 = .005,and no interaction effect, F (1, 34) < 1, η2 = .03. At Recap 7, participants in theovert condition correctly recalled 83.1% of the phonemes (SD = 20.8), whereasparticipants in the silent condition correctly recalled 74.9% (SD = 21.9).

Criterion analysis. At an adjusted α level of .69, the between-group effect onlearning would still be insignificant at the phoneme level, but not the syllable orword level. For the interaction (α = .60), differences between accuracy in termsof phonemes and syllables would still be insignificant, but accuracy in terms ofwords would be significant.

For adjusted alpha levels on the retention measure, the between-group ef-fect would be significant (α = .75) at the word, syllable, and phoneme level.However, the interaction would be significant only at the syllable and wordlevel.

Discussion

The power analysis here confirms that this experiment comes closest to demon-strating an effect of overt repetition on WL, perhaps because of the additionalmanipulation that conferred an extra presentation on participants in the overt rep-etition condition. Participants in this experiment showed the most robust learningand the least forgetting of any of the three experiments reported here. Under veryrelaxed (to the point of being unreasonable) alpha levels there are effects of overtrepetition, but we again stress that these effects are incredibly small (η2 = .0002–.04) compared with the extremely robust learning (η2 = .57–.68) shown across allconditions and measures of learning.

Thus, there again was clear evidence of learning in the silent condition but noevidence for a benefit of overt over silent repetition nor for a benefit of silent overovert repetition, during a task involving expressive WL. As in Experiments 1 and2, the present experiment would in most cases have detected moderate or largeeffects of condition, or of the Condition × Recap interaction with power of .80.The effects, however, are of small magnitude. The results provide further evidencethat overt repetition does not substantially benefit expressive WL, although onceagain, the possibility remains of a small beneficial effect accounting for about1–2% of the variance.

However, there is one effect, the between-group effect for retention, for whichwe only have the sensitivity to detect a large effect ( f ≥ .42). It is also clear that


there is a large amount of variance in the overall performance of both groupsin these three experiments, which reduces the experimental sensitivity of eachexperiment. However, we now have data from three experiments with identicalstructure and nearly identical procedure up until Recap 7. To increase the samplesize, and hence, the sensitivity of the analysis, therefore, we undertook a meta-analysis of data from all three experiments before drawing our final conclusionsabout the benefit of overt repetition.

Meta-analysis

To achieve the power of .80 that we were previously achieving through adjustmentsto the alpha level of our statistical tests, an impractical number of subjects wouldneed to be run in this paradigm. For the between-subjects effect of our mainmanipulation, overt repetition versus silent, a total sample size of 298 participantswould allow us sufficient power (.80) to detect a small ( f = .10) effect on eachmeasure of learning. For the interaction effect, an N value of 188 is needed todetect a small effect. Medium effect sizes can be detected with much more modestgains in sample size (N = 50 for the between-subjects effect; N = 32 for theinteraction effect, which we have already achieved).

For the small effects of our manipulation on retention, even larger samplesizes would be needed. The between-subjects effect on retention requires 592participants, and the interaction requires 200. For medium effects, 98 participantsis still needed for the between subjects effect and 34 is needed for the interaction.

For the meta-analysis, the data from all three experiments was combined result-ing in 108 participants with 54 participants who had been in the overt condition and54 participants who had been in the silent condition. The same type of analysisas Experiments 1, 2, and 3 was conducted, except experiment was added as afactor to ensure our assumption of no difference between experiments is valid.Thus, we conducted a 3 (Experiment)×2 (Condition)×6 (Recap) ANOVA anda 3 (Experiment)×2 (Condition)×2 (Recap) ANOVA for words, syllables, andphonemes recalled.

The increased sample size resulted in greater sensitivity compared with Experi-ments 1–3 individually, while maintaining power at .80. For effects across Recaps1–6, sensitivity increased from being able to detect effects of f ≥ .29 to detectingeffects of f ≥ .17 (η2 ≥ .03) for the main effect of condition and from f ≥ .23 to ≥.12 (η2 ≥ .015) for the Condition×Recap interaction. For effects across Recaps6–7, sensitivity increased from f ≥ .42 to ≥ .24 (η2 ≥ .05) for the main effectof condition, and from f ≥ .24 to ≥ .14 (η2 ≥ .02) for the Condition × Recapinteraction.

Results

Experiment factor.

SHORT-TERM LEARNING. No main effect for experiment was found in the 3×2×6 ANOVAs conducted on the accuracy scores for words, F (2, 102) = 1.45,p = .24, η2 = .006 (F [2, 102] = 1.64, p = .20, η2 = .03), syllables, F (2, 102) < 1,


η2 = .01 (F [2, 102] < 1, η2 = .01), and phonemes, F (2, 102) = 1.03, p = .36,η2 = .02. There was an interaction between experiment and recap for wordsrecalled, F (10, 510) = 2.82, p < .05, η2 = .05 (F [10, 510] = 2.39, p < .01, η2 =.05), syllables recalled, F (10, 510) = 2.08, p < .05, η2 = .04 (F [10, 510] = 2.05,p < .05, η2 = .04), and a borderline interaction for phonemes recalled,F (10, 510) = 1.61, p = .10, η2 = .03. Post hoc ANOVAs using a Bonfer-roni corrected α of .017 at each level of the dependent measure that displayeda significant interaction (i.e., word and syllable) revealed that the effect wasdriven by a steeper learning curve in Experiment 1 compared to Experiment3 and Experiment 3 compared with Experiment 2 for words, Fs (5, 350) >3.20, ps < .01, η2s > .04 (Fs [5, 350] > 3.23, ps < .01, η2s > .04) and amarginal effect for Experiment 1 compared to Experiment 3 for syllables, F (5,350) = 2.22, p = .05, η2 = .03 (F [5, 350] = 2.13, p = .06, η2 = .03). Experiments1 and 2 did not differ significantly for either words or syllables recalled, Fs (5,350) < 1, η2s < .01 (Fs [5, 350] < 1, η2s < .009).

It is critical that the effect sizes of the experiment factor are small and we foundno interaction between experiment and condition, Fs (2, 102) < 1, η2s < .008(Fs [2, 102] < 1, η2s < .005), and no three-way interaction between experiment,condition, and recap, Fs (10, 510) < 1, η2s < .02 (Fs [10, 510] < 1, η2s <.02).

LONG-TERM LEARNING. No main effect for the experiment was found in the3×2×2 ANOVAs conducted on the accuracy scores for words, F (2, 102) = 1.40,p = .25, η2 = .03 (F [2, 102] = 1.31, p = .27, η2 = .03), syllables, F (2, 102) =1.14, p = .32, η2 = .02 (F [2, 102] = 1.13, p = .33, η2 = .02), and phonemes,F (2, 102) = 1.33, p = .27, η2 = .03. In addition, there were no interactions betweenexperiment and recap for words, F (2, 102) < .1, η2 = .002 (F [2, 102] = 1.53,p = .22, η2 = .03), syllables, F (2, 102) = 1.11, p = .33, η2 = .02 (F [2, 102] =1.27, p = .29, η2 = .02), or phonemes recalled, F (2, 102) = 1.90, p = .16,η2 = .04. Again, we found no interaction between experiment and condition,Fs (2, 102) < 1, η2s < .006 (Fs [2, 102] = < 1, η2s < .004), and no three-wayinteraction between experiment, condition, and recap, Fs (2, 102) < 1, η2s < .009(Fs [2, 102] < 1, η2s < .007). These results, in conjunction with the short-termlearning results, suggest that collapsing across experiments is warranted and thatno problematic differences between experiments exist. The meta-analysis may beintroducing some further error variance into the ANOVAs that we are reporting,but they do not involve the between-subjects manipulation and we can still beconfident that we are achieving gains in power by collapsing across these threeexperiments. The result of this averaging is depicted in Figure 4 for each of ourthree measures.

Words. The 3×2×6 ANOVA found a main effect for recap, F (5, 510) = 79.17,p < .01, η2 = .42 (F [5, 510] = 78.18, p < .01, η2 = .43), no main effect ofcondition, F (1, 102) < 1, η2 = .0005 (F [5, 510] < 1, η2 = .00001), and nointeraction effect between recap and condition, F (5, 510) < 1, η2 = .0034 (F [5,510] < 1, η2 = .002). Averaging across all three experiments, the overt condition

Figure 4. The overall performance for participants averaged across all three experiments(N = 108). Performance is plotted separately in terms of (top) words, (middle) syllables, and(bottom) phonemes correct. Error bars are standard errors.


recalled 47.2% (SD = 33.9) of the words at Recap 6, whereas the silent conditionrecalled 44.0% (SD = 29.9).

The 3 × 2 × 2 ANOVA showed a main effect of recap, F (1, 102) = 19.64,p < .01, η2 = .16 (F [1, 102] = 16.23, p < .01, η2 = .14), no effect of condition,F (1, 102) < 1, η2 = .01 (F [1, 102] < 1, η2 = .004), and no interaction effect,F (1, 102) < 1, η2 = .01 (F [1, 102] < 1, η2 = .01). At Recap 7, the overt conditionrecalled 39.4% of the words (SD = 32.1) and the silent condition recalled 32.9%(SD = 29.9).

Syllables. The 3 × 2 × 6 ANOVA found a main effect for recap, F (5, 510) =150.62, p < .01, η2 = .58 (F [5, 510] = 149.82, p < .01, η2 = .60), no maineffect of condition, F (1, 102) < 1, η2 = .0001 (F [1, 102] < 1, η2 = .58), and nointeraction effect between recap and condition, F (5, 510) < 1, η2 = .005 (F [5,510] < 1, η2 = .0000007). At Recap 6, the overt condition recalled an average of65.7% (SD = 27.4) of the syllables and the silent condition recalled 65.0% (SD =27.1).

The 3 × 2 × 2 ANOVA showed a main effect of recap, F (1, 102) = 24.45,p < .01, η2 = .19 (F [1, 102] = 23.89, p < .01, η2 = .19), no effect of condition,F (1, 102) < 1, η2 = .005 (F [1, 102] < 1, η2 = .004), and no interaction effect,F (1, 102) = 2.19, p = .14, η2 = .02 (F [1, 102] = 2.54, p = .11, η2 = .02). AtRecap 7, the overt condition recalled 59.4% of the syllables (SD = 27.1) and thesilent condition recalled 53.2% (SD = 27.5).

Phonemes. The 3×2×6 ANOVA found a main effect for recap, F (5, 510) =191.48, p < .01, η2 = .64, no main effect of condition, F (1, 102) < 1, η2 = .001,and no interaction effect between recap and condition, F (5, 510) = 1.09, p =.36, η2 = .01. Averaging across all three experiments, the overt condition recalled79.7% (SD = 20.5) of the phonemes at Recap 6, whereas the silent conditionrecalled 80.1% (SD = 21.5).

The 3×2×2 ANOVA showed a main effect of recap, F (1, 102) = 38.13, p <.01, η2 = .26, no effect of condition, F (1, 102) < 1, η2 = .004, and an interactioneffect, F (1, 102) = 4.34, p < .05, η2 = .04. At Recap 7, the overt conditionrecalled 73.8% of the phonemes (SD = 32.1) and the silent condition recalled68.3% (SD = 26.6).

Criterion analysis. Given the power of this meta-analysis, more reasonable ad-justments to alpha level can be made; however, such adjustments change the resultsreported above in only one case. The adjusted α level for the main effect of themanipulation on learning is .38 and the interaction between condition and learningis .22. Such adjustments would not change the results in terms of words, syllables,or phonemes correct. Thus, we have evidence for accepting the null hypothesisthat overt repetition has no more than a small effect on learning in this paradigm.In terms of retention, the adjusted α level for the main effect of the manipulationis .61, and the adjusted level for the interaction is .22. Such adjustments wouldnot change the results of these tests in the case of the main effect. It wouldchange the results of the tests of the interaction using syllable and phoneme levelsof accuracy, but not whole words. Thus, we can accept the null hypothesis that


overt repetition has no more than a small effect on the retention of words, butmay have a small (between .10 and .14) effect on the retention of syllables andphonemes.

Discussion

The meta-analysis reveals that across all three experiments, the silent condition isclearly demonstrating learning for each of our three measures. However, acrossall three experiments, the overt condition is nearly indistinguishable from thesilent condition. Furthermore, there is clearly enough learning during the expo-sure portion of the experiments and forgetting during the task filled delay toreveal differences between repetition conditions in acquisition or retention, if suchdifferences existed. This is evidenced by the strong main effects of recap in the3×2×6 and 3×2×2 ANOVAs. What is not revealed is a significant differencebetween the overt and silent conditions in either the overall learning or retention,or the rate of learning or forgetting. The one difference in the rate of forgettingthat does emerge is in terms of phonemes recalled, with little indication that thisdifference affects the total number of whole syllables or whole words recalled.Further, this effect was not exacerbated by the longer retention interval imposedin Experiment 2. Both of these facts suggest that the functional significance of thiseffect is limited.

Thus, we conclude that expressive WL can occur without overt repetition, andthat overt repetition is therefore not critical to expressive WL as it is operationalizedin this task. Experiments 1–3 and the subsequent meta-analysis indicate that overtrepetition is not critical. In addition, all three experiments and the meta-analysisindicate that overt repetition is not beneficial either. The last question that we ask iswhether or not a purer measure of expressive word form learning, one that does notinclude any semantic information, might reveal a critical role for overt repetition.It may be that the additional semantic component (i.e., mapping the phonologicalform to the alien) of our expressive word-learning task provides supplementary,or alternative, means to learning in the silent condition.

Accordingly, we conducted two further experiments employing a purer form ofphonological learning. It may be the case that the components of the WL task thathad participants learn the meanings that are given to the nonwords (i.e., the aliens)is masking an effect of overt repetition in the WL task. A task whose variancewould be attributable to only phonological word form learning and that focusessolely on learning the sequence of phonemes associated with a new word is annonword repetition (NWR)-priming task.

This method is discussed and offered as a paradigm for studying word formlearning by Gupta and colleagues (Gupta & Cohen, 2002; Gupta & Dell, 1999).In this paradigm, the participant is exposed to a set of novel word forms multipletimes, repeating each one immediately after its presentation, which is the same asin the expressive WL paradigm of Experiments 1 to 3. Unlike the paradigm usedin Experiments 1 to 3, however, there is no referent to which the novel word isto be attached. Learning in this task thus incorporates a subset of the processingrequirements of the paradigm of the previous Experiments: in terms of the discus-sion in the introduction, the requirements to learn a semantic representation, andto learn the link between the phonological and semantic representations are here


eliminated. The learning observed in this paradigm thus constitutes expressive WLthat is purely phonological, and without any semantics, and the rationale for useof this task was to examine purely phonological expressive word form learningmight reveal an effect of overt repetition.

An NWR-priming task involves the presentation of novel auditory stimuli toparticipants. With each presentation, participants traditionally overtly repeat thestimulus just as they heard it. Multiple exposures are given by designating a setof the nonwords as “repeat” stimuli and a set as “unique” stimuli. Repeat stimulioccur in every block of presentation, whereas unique stimuli occur only onceper experiment. Thus, during the final block of the experiment priming can bemeasured as the difference in repetition ability (in terms of accuracy) for therepeat stimuli versus the unique stimuli for that block. This learning is referred toas repetition priming. In the present study, we investigate repetition priming forsix-syllable nonwords and the effect of overt repetition on such learning.

EXPERIMENT 4

In Experiment 4, we simply aim to establish that priming (measured as a greaterincrease in overt repetition accuracy immediately following stimulus presentationfor repeat stimuli than for unique stimuli) is evident at this length before turning,in Experiment 5, to the question of whether the act of overt repetition is the sourceof this priming.

Method

Participants. Twenty-four participants were involved in this experiment. Sixteenparticipants were recruited through a posting on the University of Iowa’s JobNetWeb site and received $8 for participating. The remaining participants were un-dergraduates at the University of Iowa and received course credit for participating.

Materials. Stimuli were six-syllable nonwords drawn from the same corpus as thefirst three experiments (Gupta et al., 2004). Stimuli were again presented throughheadphones via a Macintosh PowerPC G3 computer using PsyScope (Cohenet al., 1993).

Design and procedure. Each participant was presented with 120 randomly se-lected six-syllable nonwords. Random selection of stimuli was done independentlyfor each of the 24 participants. Stimuli were grouped into seven blocks of 30nonwords each. Fifteen of the 120 six-syllable nonwords selected for presentationwere randomly designated as the “repeat” stimuli and appeared in each of the sevenblocks (see Appendix E for nonwords used as “repeat” stimuli). The remaining105 nonwords designated as the “unique” stimuli. The unique nonwords wererandomly distributed across the seven presentation blocks and were presentedonly once to each subject.

On each trial, a nonword was presented and a fixation cross appeared on thecomputer display immediately following the offset of the nonword. This crossremained on the display for 500 ms. Participants were instructed to repeat eachnonword as soon as the fixation cross appeared. Both the stimulus presentation and


participant responses were recorded on audiotape for subsequent offline scoringof repetition accuracy. The next nonword was presented 6,000 ms after the onsetof the previous nonword.

Participants were allowed a brief break and were provided with water to drinkbetween blocks.

Scoring. For repetition accuracy, a strict scoring criterion was used. A syllablewas scored as correct if and only if it was repeated at the correct serial position andall phonemes were correct, unreduced, and in the correct serial order. A nonwordwas scored as correct if and only if each syllable in the response was correct andno additional syllables were appended. We did not analyze accuracy in terms ofsyllables correct or phonemes correct, as these analyses yielded little increase insensitivity in Experiments 1 through 3.

Results

A 2 (Stimulus Type)×7 (Block) repeated-measures ANOVA indicates a significantmain effect of both type and block, F (1, 23) = 8.74, p < .01, η2 = .29 andF (6, 138) = 3.32, p < .01, η2 = .13, respectively. A significant interaction,F (6, 138) = 2.47, p < .05, η2 = .10, further indicates that the change in accuracyacross blocks is greater for the repeat stimuli than for the unique stimuli, the latterof which shows little to no improvement across blocks.

Discussion

Experiment 4 demonstrates significant priming can be achieved in an NWR-priming task using six-syllable nonwords as the stimuli to be learned. We turnnow to the role of overt repetition in this learning.

EXPERIMENT 5

The logic for Experiment 5 is the same as in the WL tasks, but here the learningis focused solely on the phonological form of the presented stimuli and learningthe link between this form and the motor processes needed to execute expressionof this form (Figure 5). There are no target–referent mappings to learn; instead,participants must simply learn the sequences of phonemes that make up eachof the repeating nonwords presented in this modified NWR-priming task. If overtrepetition is either critical or beneficial in learning the phonological representationsof new words, then participants who do not experience this repetition should showeither no priming or less priming than participants who do overtly repeat followingstimulus presentation.

Method

Participants. Thirty-six participants were involved in this experiment. All wereundergraduates at the University of Iowa and received course credit in exchangefor participation.

Figure 5. The nonword repetition accuracy as a function of condition (silent vs. overt) and word type (unique vs. repeat). Because of thenature of the experimental paradigm, unique nonwords have data points for Blocks 1 and 8, whereas repeating nonwords only have data pointsat Block 8. The graph depicts a significant difference between unique and repeat nonwords at Block 8 but no differences between the silentand overt conditions. Error bars are standard errors.


Materials. The stimuli were of the same type as those presented in Experiment4 and were presented using the same experimental apparatus (see Appendix F fornonwords used as “repeat” stimuli).

Design and procedure. The design and procedure were the same as Experiment 4,except that participants completed eight blocks of NWR, with Blocks 2–8 utilizingan NWR-priming design. In Block 1, all participants were presented with 40nonwords, all of which were unique stimuli as previously defined. Participants inboth conditions completed an NWR task with these stimuli, overtly repeating thenonword as quickly and as accurately as possible following the onset of a fixationcross that appeared at stimulus offset. This provided a baseline NWR measure forparticipants in both the overt and silent conditions.

Following this first block, participants went through six blocks of an NWR-priming paradigm; however, only half (N = 18) of the participants, those who wererandomly assigned to the overt condition, actually performed an overt repetitionin response to a stimulus presentation. The other half of the participants, thosewho were randomly assigned to the silent condition, were merely exposed to astimulus presentation and were instructed to say the word to themselves in theirmind without actually producing a sound or moving their mouth. In other words,they were instructed to engage in internal repetition or rehearsal. This instructionwas given to reduce ambiguity as to the strategy engaged by participants in thesilent condition. Thus, in both conditions, participants engaged in articulatory–phonological planning. However, in the overt condition, participants in additionexecuted the articulatory–phonological plan. Again, there were 40 stimuli withina block, and 29 of these were repeat stimuli and 20 were unique stimuli. Theunique stimuli occurred only once, whereas the repeat stimuli appeared once inevery block from Blocks 2–8.

In the final block, participants in both the overt and silent condition wereinstructed to overtly repeat the nonword stimuli upon presentation. This procedureprovided a measure of accuracy on the repeating stimuli for the silent conditionthat was based only on the number of exposures participants in this conditionreceived, not on the ability to overtly repeat the stimulus.

Scoring. For repetition accuracy, a strict scoring criterion was again used. Forthe overt condition, performance for the unique stimuli in Block 1 as well as theunique and repeat stimuli for Blocks 2–8 was measured. For the silent condition,performance for unique stimuli in Block 1 as well as the unique and repeat stimulifor Block 8 was measured.

Results and discussion

An analysis of the available data for the overt condition’s repetition of repeatstimuli (Blocks 2–8) shows improvement on these stimuli across blocks. A 2(Stimulus) × 7 (Block) repeated-measures ANOVA revealed a main effect ofstimulus, F (1, 17) = 22.44, η2 = .57, p < .01, no main effect of block, F (6, 102)< 1, η2 = .05, but an interaction, F (6, 102) = 3.57, p < .01, η2 = .17. Thus,participants in this condition show gains in accuracy on the repeat stimuli relativeto the unique stimuli that lead to the significant interaction. Post hoc contrasts


motivated by the significant interaction reveal no difference between Block 2 andBlock 8 on the repeat stimuli, F (1, 102) = 1.43, p = .23, η2 = .10, but a differencebetween unique stimuli in the same Blocks 2–8 comparison, F (1, 102) = 8.95,p < .01, η2 = .29. When performance on Blocks 2 and 3 are pooled togetheras a measure of initial performance and Blocks 7 and 8 are pooled together as ameasure of final performance then a significant effect is uncovered for the repeatstimuli, F (1, 17) = 4.18, p < .05. The same pooling also strengthens the effectfor the unique stimuli, F (1, 17) = 10.52, p < .01. Thus, priming was observed inthe overt condition as in Experiment 4.

The question of primary interest, however, related to learning in the silentcondition relative to the overt condition. To address this question, we examinedBlock 8 NWR accuracy in a 2 (Condition) × 2 (Stimulus) repeated-measuresANOVA, which revealed no main effect of condition, F (1, 34) < 1, η2 = .007, amain effect of stimulus, F (1, 1) = 21.05, p < .01, η2 = .38, and no interaction,F (1, 34) < 1, η2 = .004. Thus, in Block 8, repeating stimuli were repeatedmore accurately than unique stimuli, this difference did not differ for the silentand overt conditions, and there was no main effect of silent versus overt. Thatis, overt repetition did not confer any repetition accuracy benefit compared withsilent repetition.

GENERAL DISCUSSION

On the question of whether expressive WL can occur without overt repetition,Experiments 1–3 and a meta-analysis of these experiments indicate that it can,whereas Experiment 5 extends this finding to phonological learning where notarget–referent pairing is necessary. Thus, overt repetition (specifically, executionof the articulatory–phonological plan of a word form) does not appear to becritical to expressive WL (specifically, to the learning of the internal phonologicalrepresentation). The results of Experiment 1 and the meta-analysis further indicatethat any benefit for overt repetition would be in the retention of information aboutthe individual phonemes of a new word, but not in any larger conglomeration basedon phonetic information (i.e., syllables or words). Experiment 2 demonstrates thatany differences in the retention of phonemes disappear over longer periods oftime that may be more important time scales for assessing language acquisition.This finding, plus the isolation of any effect to the phonetic level, questions thefunctional significance of any observed differences between the overt and silentconditions of these studies. Experiment 3 neutralizes the role of immediate repe-titions of a stimulus in terms of aural benefits by showing that participants in thesilent condition show no learning benefit to two exposures of a nonword stimuluswithin a very short time period. Last, Experiment 5 validates the conclusions fromthe WL paradigm and extends them to a purer case of phonological learning in anNWR-priming study, which does not include any information about the meaningsof nonwords, only their phonological forms. Experiment 4 simply established theparadigm of Experiment 5 as one that has a learning component, and can thus beused to evaluate differences in learning between groups.

How do these results compare with those of previous studies? In Siebert’s (1927)investigation of French and English vocabulary pairings, he reported no benefit


for repeating a list of paired associates aloud during learning at the first test ofproduction accuracy (measured by written, not spoken, response). The presentfindings are consistent with this, showing learning without overt repetition, and nobenefit of overt repetition, but extending the finding to spoken responses. Siebertalso found a benefit of overt repetition at delayed tests of accuracy and savings forlater relearning. Although a similar result was obtained in the present Experiment 1,this did not replicate in Experiment 2. What leads to the difference? There areat least three differences between the learning situations. First, the studies dif-fered in novel word presentation modality (visual in Seibert, auditory in thepresent study). Second, they also differed in novel referent presentation modal-ity: Siebert’s study asked participants to associate the novel word from to itsnative-language translation equivalent, rather than to a visual referent, as in thepresent experiments. Third, the studies differed in response modality (written vs.spoken).

We suggest that the key difference may be the use of verbal versus visualreferents. This is suggested by the findings of Duyck et al. (2003; Experiment 2),who showed that articulatory suppression had an effect on the short-term acquisi-tion of vocabulary (suggesting that articulatory–phonological rehearsal was likelyto play a beneficial role) when the task was to learn word–nonword pairs (i.e.,verbal referents, as in Seibert’s 1927 study), but had no effect when the nonwordsthemselves, had an association with a visual referent (a situation more akin tothe present experiments). This finding suggests that articulatory–phonologicalplanning, and therefore also overt repetition, may be beneficial when verbal ref-erents are used, but not when visual referents are used. Furthermore, Duyck et al.(2003, Experiment 3) obtained the same result in adolescents employing auditorypresentation of the novel words. This suggests that presentation modality is not thekey difference differentiating Seibert’s results from ours. It is, in addition, possiblethat the findings may differ as a result of the difference in response modalities:with written responses, overt repetition may add a delayed cross-modal benefit,but no such cross-modal benefit accrues for spoken responses. These hypothesesare consistent with the benefits of articulatory–phonological planning reported byEllis and Beaton (1993) and Papagno et al. (1991) in studies that employed writtenor typed responses rather than spoken responses and used verbal rather than visualreferents, again suggesting that any benefit of overt repetition may accrue onlywith written responses and/or without a visual referent.

Participants in all of the studies discussed thus far (including the present one) arenormal, college-age adults with roughly 18 or more years of experience producingwords in their native language. The present stimuli maintain phonological andphonotactic regularities within the participant’s native language and this concor-dance could significantly reduce the learning problem faced by the language pro-cessing system and weaken the role of overt repetition as a mechanism for gaininggeneral experience with one’s language and the articulatory processes associatedwith expressive language. Thus, although many studies have used college-ageadults to investigate the issues addressed by these experiments, it may be thatthe issue is a more prominent one in younger children who are actively engagedin the language acquisition process or older children acquiring a language thatuses an unfamiliar phonology. Although the previously cited studies did examinethe acquisition of foreign languages, most had relatively similar phonologies to


participant’s native language and/or have the difficulty that no spoken responseswere ever required of participants.

Overall, our data suggest that overt repetition (and in particular, execution ofarticulatory–phonological plans) is not critical to establishment of phonologicalrepresentations in expressive WL; that is, that the acquisition of new words to thepoint that they can be recalled and produced when cued with semantic information,or immediately following their presentation, can be achieved without such overtrepetition. This conclusion holds true whether both the phonological form andthe meaning of a word are to be acquired or just the phonological form is beingacquired. Moreover, overt repetition does not appear to confer any benefit. Thislatter conclusion, however, may apply primarily to the situation where expressivelearning is gauged through spoken rather than written or typed responses, andwhere the referent of the novel word is visual rather than verbal. This situationis reasonably similar to that of much preliterate WL. In situations where the ex-pressive learning involves referents that are translation equivalents without visualsupport and/or where the response is written rather than spoken (as is typical insecond language instruction), overt repetition may, indeed, confer a benefit, as hasbeen widely supposed to be the case for second language learning.

APPENDIX A

STIMULI FROM EXPERIMENT 1

The stimuli used in “target” sets are in bold.

babitade dasotut gisabifbalimot daterene gisuninbalugake davekik gitotisbanareke dedalete kadonekebasodote degarite kafasenebatoken dekerume kafironbebinege delanose kanesavbedesor dipanen kanesuvebegalif disasus kekabagebemasute disokebe kekaranebesunete ditomis kepibopbimopun donakebe keratotbinasig donaner kerilosbirasin doninene kevaratebisirel dukalede kikirekbodedite dulenan kiledegebofogad dutenet kilorirbonikak gakilire kinatetbonitet gedeneg kirigedeborokite gefirase kirikoddafetak gemelole kisumepedagadabe genovake kitetuldaketane gesinefe kiturundakotul getedeb kodigildaselipe ginatip kogolil


komasol porodeg teguvokkufesade potapofe telunarpasakese potedele terebenpatalit pumadose tesokanepelugeke putonite tesurukpenedeke tadasibe tetitilepesadeb tademal tilisekpesidide taganofe tirenelepilesit tagukit tisenenpinopes takudek toginonpirogege tapudan toverukpisisope tavasad tovupuspokibote tebidov tovutokepomikog tedanale tudemarponetase tefelose tugisuke

APPENDIX B

Figure B.1. Four “target” alien images from Experiment 1.


APPENDIX C

STIMULI FROM EXPERIMENT 2 DAY 1


balevel ditivese kukiretebalugake divigure kukurenebanareke doganov kuresenbatikude doninene pamutetbebinege dorageg papagesbekinore dosetote pekigokbemasute dosisis pelugekebenerad dotebat penedekebenutite duniseb petafudbesunete dupodofe pevanafbinenule dusenane pevotodebipetog gataton pifeketebisateke gatofob pirogegebisefem gedeneg pisitelbodenose gemelole ponulipbofenene genetik popisonbofogad genonuf potononbokonip gepagos putonitebolutol gepiroke tadasibebomisul gibanoke tademalbonitet gitotis tafadusbosapen gosefer takudekbosurike kakikot tedanalebotunoge kalemese telunarbukesede kamutin tenosanbusagite kariride terebendalovet kedosil tesokanedarusete kegulol tesurukdaselipe kekesuke tetevasededalete kenatap tilevonededilus kepefal tinosokedegoruge kerilos tiremundekedol kesatep togogemedekerume kesonet tokarenedeketig kiledege toreretdekutan kinatet totifitedesafene komasol totikoredesudore konanope tudemardetasene konatot tukogemdimaset korumene tutefele


APPENDIX D

STIMULI FROM EXPERIMENT 3


bafoted dofenis kosirimebakunel doganov kosotilebaliseb donakebe kukiretebanisite donaner kurotitbatitene doninene papagesbatoken dosekase pebasapbebinege dosetote pevanafbekinore dosisis pevotodebenisure dukalede pifeketebesunete dupodofe pisamovbetenege dusimase pomikogbifetet dutenet ponulipbimopun galanan potutombinelud gatofob putonitebinenule getedeb tasiborebinonere gevutide tavakesbipetog gitotis tavasadbirasin kadoneke tefelosebisirel kafiron tefilibbisonir kagapone teguvokbofogad kalemese temeremebonikak kamutin tenosanbosalere katepite tesetitbosurike katigal tesokanebulinep kedosil tesurukbusagite kekabage tetevasedabibup kekarane tevadegdagadabe kepibop tibefosedaterene keratot tiremundavatas kerilos tireneledebusiv kesonet tisatefdekutan kiledege tisenendelanose kilorir tokarenedelesep kirigede tokataredesudore kisumepe tovupusdimasat kitetul tudemardisasus kobepage tufaneddisokebe kogolil tugisukeditomis konikale tukogemdodolek konovose tutefele


APPENDIX E

STIMULI USED IN “REPEAT” SETS IN EXPERIMENT 4

badetarerikik biregonategife dasivunitudase domanumonalinbadidadodukik biretukekekote datarikitenur donosenesanutbakakitasemud bisekevedikak datovudatitek doretedonisanbakerematinem bisetegekirite davokisesoguge dorodanunatasebakidinetorope bisorelaniboke dedasesosotit dosasamodatadebalavodisabor bitanelirolak dedesonenenet doserarosepukbalidarutifad bivekotatotos dedulenelumug dotiditinakakebamekikotepav bofomamivilade defusebonitag dovikonetupesebaminenanonad bogobavikitin degasunetekake dudatotitigatbanatelobunid bokedalamipev degogerabutet dutifotodotutebanosomasalem boketesikesale dekanomegotupe gabasefepeledebanumerenesane bokikoletinef dekedidegagape gagisetonanirbapetigatinat bokogitenuvet dekediderakete gamikenefapekebaripenalisute bolesitenerir delonimasakid ganitosavekosbatisiritafabe bolimebagotem delumenafegos gasiteniliserebefonemovibaf bolipifafodore denetivoketure gategalosesasbegaditosemade bonananimileme denitekinonofe gatodinunidovebegotepetesas bonosogananed denodanukidase gavebogavanekbegotetonafuk boralenerisan depunudagekik gedarudugetapbekevesenebeke bosanutigigese desasenagibep gekipireninatbekotivepasen bosedesisinipe desiredoperute geletekeselatebelukelefises bosedigamodim desodenatolade gemokasatatanbenitipanaret bovenotadinil detelefinisan gemuvetinonokebepisafosorif budisetelebone detusedulilebe genefisodifoneberaronefarake budupisedukos diditivavemite gepelatovabekbeselatagorar bunenedesivise didutedepitate gepolomabilutebesitanedatem bupotosanenet digidetegefase gerotefuvulenebesotokamipufe dabemuvulanet dikilokelalin gesanotisesipbetebetudenofe dadasetelelole diritonononate gevakutetonofebetitalenotine dadikakitarase disekotakakare gifenokuvidivebevesesekamute dafonipisomot disesemerinise gikakemekopekbevotopulimep dagelobetabet disolekimapan giletimosematebidovekakasek dagetekununate ditalofavoras gimekofenamodbikagometesive dakesesotosek ditasenuredos gisanebililutbikamumorolese dakinisedolete ditoresogilike gisetalakenesbikativinisime dakotetatasip ditotesaneteke gitonetitikesbilegepiteseg dakupadivekek divunadefapane godapibarotebbilotatimeted danirepulurat dodasesikeron godosirometirebimekanigarote daresefaliren dodesogebonen gogirivaresosebinesetesodes dasalofelatik dofuvimesisote gomimomariranbinikemulosod dasegorenedale doketekosenome gonedemokubevbipibunosenese dasetolakaken dolarobatelose gopatanitafave


gosetidikodele kipoderutavib pesugamokoneke tenufinudinubegusutiporoneke kiridevuvatepe petobigidadas terenatomimedegutanolunetise kiriditeteteb pidatatakutase tereseriferesegutesofegipoke kirilekadasede pidikudovenus terokesisisorkadafofusafeg kirimutirelole pidinabatitob tesadonekadatekakedatabesif kisatinotanis pigadonatonule tesakalolelonekalasatatasik kisinekepoden pigidosenekese tesesumetanetkaleropevasete kisononigeset pimetonekedud tetadutotunomkamefekekaton kitidokenubet piridaledokok tetegatudodirkanesekunedas kitolupugeses pirisepivovade tetekadikepitkanokegarasole kobetevafefat pitamesefarik tetitatanufunekarotovadikene kobomatakelot pivakesusaseme tetoditinipiskasalusesetil kofukogikukafe pogigusarorube tetomelanenusekasasasesudag kokinadakineme polasudasonin tevigenemedemkatutosedetoke kolesasosatab pomanikorenule tidegatikegotekebetulesisate konerekipetak porekitalevuge tidosokamepenkegitedonatot kopireribetim posobasogufile tinaderomubovekekofemifurame korogodesikede pugetisitibuke tinadokefelomekelegelefemef kosaketakutog purinakusaviv tiradigenitotekemonumerunoge kotasogusadame puronemifisas tiredagaselipekenefafenidele kotidomoverade tabokadakitel tisodakekoteskepanasekelule kotumutafapak tabokedobemame titekopimirevekepegemadipel kotusedakelif tabomitafosone titenekekimefekepotekisodin kovotunerukere tadukenokapon titosagesagotekerefisonuruse kovuredemedose tagiditerenun tobolululolotkerositumidise kudunokakefete takikelivenese todepimositekkesidubemikose kunekotanisale takilununedif tofasanonegurekesinififadede kuneragikitap tamenonesoleg tokenigosarikkesubitoporase kunoratinepede tanobefototine tokigokavetenketesoseporole kusulevogunir tapekepodatune tonebunanamerketibetetasit padegeredinis tapenodutifame tonegudetirolketileponoguge padevenorakag tasanituregus tonemiloresumketuripavedaf padilenenunole tataketusinote tonimadunesadkevanolevevike panemalakilek tatanesurunike toredekisakevekiderikidokon parevadikokese tatavepikanuk tosanarudunamkikegelegidev patebenisatode tatukisinisige tosonenukidotekikilesevenem pedolelurarege tebovukokipil totakiserikenkikosikosulig pegebulamekap tededuvupetere totalosanudibekikosotedunune pegegelutesege tedoserutokar tudikosesedenkilelakomomige pekikipebarele tedotolekusane tukibepikaselkilidunudoves pekusadavogik tefevoferibete tunamudabenorekilitidonegus pelisibevemog tekuselotaton tunokitapaletkimatitegutate pelivitidasop telititagarife tusapedonilelekinapogedasaf peloninemiker tenakotetanoke tusotanopisolekinelasesilav pesatatevogupe tenananebasis tusubipanasenkinonoburoseme pesosanuresepe tenivorilekeg


APPENDIX F

STIMULI USED IN “REPEAT” SETS IN EXPERIMENT 5

badidadodukik kadafofusafegbanumerenesane kepotekisodinbekevesenebeke kesidubemikosebekotivepasen ketesoseporolebesitanedatem kiderikidokonbetebetudenofe kikosikosuligbikamumorolese kinelasesilavbitanelirolak kinonoburosemebivekotatotos kirimutirelolebolimebagotem kofukogikukafebolipifafodore konerekipetakbosanutigigese kovuredemedosedafonipisomot panemalakilekdagelobetabet pekikipebareledakupadivekek petobigidadasdasalofelatik pidikudovenusdatovudatitek pirisepivovadedavokisesoguge polasudasonindesasenagibep tabokadakitelditotesaneteke tagiditerenundodesogebonen tapekepodatunedomanumonalin tatanesurunikedoserarosepuk tatavepikanukdovikonetupese tebovukokipilgasitenilisere tefevoferibetegategalosesas tekuselotatongemokasatatan tenakotetanokegemuvetinonoke tetitatanufunegonedemokubev tokigokavetengopatanitafave tonegudeti

ACKNOWLEDGMENTSThe authors thank Sara Evan, Charles Geilenfeld, Jon Hintz, Melissa Hodapp, JohnLipinski, Byron Murphy, Anna Napawan, Sierra Spies, Liz Tener, and Matthew Woodinfor their assistance in setting up and running the experiments presented here and membersof the Language Discussion Group at the University of Iowa for helpful discussion of theresults. Experiments 1 and 3 were previously presented at the 46th Annual Meeting of thePsychonomic Society, Minneapolis, MN. This research was partially supported by GrantNIH R01 DC006499 (to P.G.).

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